2,6 Dihalobenzyl ethers

ABSTRACT

wherein R1 is alkyl: R2 is alkyl, aryl or aralkyl; R3 is hydrogen or alkyl or R2 and R3 together is polymethylene; and R4 is 2,6-dihalobenzyl are useful as herbicides.   Compounds of the formula

United States Patent Barker et a1.

2.6 DIHALOBENZYL ETHERS Inventors: Michael D. Barker, Maidstone;

Eirlys R. Isaac. Sittingbourne; Peter Kirby. Muidstone; Graham C. Smith.Rumsgute. all of England Assignec: Shell Oil Company, Houston, Tex.

Filed: June 21, [974 Appl. No.: 481.723

LLS. C1. 260/3409; 77/88; 260/3407 Int. Cl. w. C07D 317/16; AOlN 9/28Field of Search 260/3407, 340.9

References Cited UNITED STATES PATENTS 4/1936 Baldwin et a1. 260/3407 1Nov. 11, 1975 Young et ill. .1 260/3407 X Kirb ct nlmv. 260/3411)Prilmlr) E\'uminer-Anton H. Sutlo ABSTRACT Compounds of the formula 2,6DIHALOBENZYL ETHERS This invention relates to 2,6-dihalobenzyl etherswhich are of interest as selective herbicides.

Accordingly the present invention provides 2,6- dihalobenzyl ethershaving the following formula:

wherein R, represents an alkyl group; R represents an alkyl, aryl oraralkyl group; R represents a hydrogen atom or an alkyl group, or R andR together represent a polymethylene group; and R represents a2,6-dihalobenzyl group.

When R represents an alkyl, aryl or aralkyl group these may beoptionally substituted, for example by one or more halogen atoms orhydroxy groups. When R represents an alkyl group this also may beoptionally substituted, for example by one or more halogen atoms orhydroxy groups. The halogen atoms in the 2,6- dihalobenzyl group may befluorine, chlorine, bromine or iodine or a mixture thereof, for example2,6- dichlorobenzyl, 2-chloro-6-fluorobenzyl, or 2,6- difluorobenzyl.

The alkyl groups represented by R R and R preferably contain l to 6carbon atoms. The aryl and aralkyl groups preferably contain up to 8carbon atoms and the polymethylene group up to 6 carbon atoms.

The benzyl ethers according to the invention which have shownconsiderable selective herbicidal activity are those in which the benzylgrouping is substituted in the 2,6-positions by chlorine and/or fluorineatoms.

Preferred compounds are:

those of formula I wherein R represents an alkyl group of 1-6 carbonatoms, for example methyl, ethyl or propyl; R represents an optionallysubstituted alkyl group of l6 carbon atoms, for example methyl, ethyl orisopropyl, or a phenyl or benzyl group; R represents a hydrogen atom oran optionally substituted alkyl group of l6 carbon atoms, for examplemethyl, hydroxymethyl, chloromethyl, ethyl or isopropyl, or R and Rtogether represent a polymethylene group of up to 6 carbon atoms, forexample tetramethylene or pentamethylene; and R represents a2,6-dihalobenzyl group, eg 2,6-dichlorobenzyl or2-chloro-6-fluorobenzyl.

A particularly preferred example of which is 4-(2,6-dichlorobenzyloxymethyl)-2,2-dimethyl-4-ethyl-1,3- dioxolane.

It will be appreciated that the compounds of the invention may exhibitgeometrical and/or optical isomerism. The individual isomers andmixtures thereof are included within the scope of the invention.

The invention includes also a process for the preparation of compoundsof formula I which comprises reacting a compound of formula:

with a strong base and a compound of formula:

R Hal wherein Hal represents a halogen suitably chlorine or bromine,atom. The strong base is suitably an alkali metal hydride, for examplesodium hydride. The reaction is conveniently carried out in an organicsolvent, for example an aromatic hydrocarbon solvent such as toluene.

As mentioned above the compounds of the invention are of interest asherbicides and the invention includes therefore herbicidal compositionscomprising a 2,6- dihalobenzyl ether of formula I together with acarrier and/or a surface-active agent. The herbicidal activity of thecompounds of the invention is exhibited particularly in pre-emergenceapplication against grass spe cies. However, the compounds show anunexpectedly low activity against wheat and may be used as selectiveherbicides against grass weeds, e.g. blackgrass, in that crop. Theinvention includes therefore a method of combating weeds in crops at alocus which comprises applying to the locus a selectively herbicidalamount of a 2,6-dihalobenzyl ether of formula I.

The term carrier" as used herein means a solid or fluid material, whichmay be inorganic or organic and of synthetic or natural origin, withwhich the active compound is mixed or formulated to facilitate itsapplication to the plant, seed, soil or other object to be treated, orits storage, transport or handling.

The surface-active agent may be an emulsifying agent or a dispersingagent or a wetting agent; it may be nonionic or ionic.

Any of the carrier materials or surface-active agents usually applied informulating pesticides may be used in the compositions of the inventionand suitable examples of these are to be found, for example, in UK.specification No. 1,293,546.

The compositions of the invention may be formulated as wettable powders,dusts, granules, solutions, emulsifiable concentrates, emulsions,suspension concentrates or aerosols. wettable powders are usuallycompounded to contain 25, 50 or w of toxicant and usually contain, inaddition to solid carrier, 15-10% w of a dispersing agent and, wherenecessary, 0-10% w of stabilizer(s) and/or other additives such aspenetrants or stickers. Dusts are usually formulated as a dustconcentrate having a similar composition to that of a wettable powderbut without a dispersant, and are diluted in the field with furthersolid carrier to give a composition usually containing -l0% w oftoxicant. Granules are usually prepared to have a size between 10 and BSmesh (l.676-O.l52 mm), and may be manufactured by agglomeration orimpregnation techniqucs. Generally, granules will contain /z25% w oftoxicant and 0-l07c w of additives such as stabilizers, slow releasemodifiers and binding agents. Emulsifiable concentrate usually contain,in addition to the solvent and, when necessary, co-solvent, l0-507( w/vof toxicant, 2-207c w/v of emulsifiers and 0-2()% w/v of appropriateadditives such as stabilizers, pcnetrants and corrosion inhibitors.Suspension concentrates are compounded so as to obtain a stable,non-sedimenting. flowable product and usually contain 10-75% w oftoxicant. 05-15% w of dispersing agents. (ll-10% w of 3 suspendingagents such as protective colloids and thixotropic agents, O10% w ofappropriate additives such as defoamers, corrosion inhibitors,stabilizers, penetrants and stickers, and as carrier, water or an or-EXAMPLE 1 4-( 2,6-Dichlorobenzy loxymethyl )-2 ,2-dimethyl-4- ethyl- 1,3dioxolane ganic liquid in which the toxicant is substantially insol- ASolution of 2 2 dimethyl 4 hydmxymethyl I n uple i Solids 9 lnorgamc 5be dioxolane (32.0 g) in toluene (25 ml) was added slowly dissolved inthe cfarrier to assistf in preventing se imento a Stirred Suspension ofSodium hydride (9.6 g of 50% or as l agents l f I dispersion in oil) intoluene (25 ml). After the addition Aquegils dlspelislons Slons or exampthe mixture was heated under reflux for 2 hours. 2,6- composmons obtameqby dllutmg. a wetlable Powder or Dichlorobenzyl chloride (39.1 g) intoluene 100 ml) 3 l l l accmdmg to the h water was then added dropwiseand the mixture heated under '2 he i'i the fi preslim li fi reflux for afurther 4 hours. The cooled mixture was .Sald emu Smns g e t e Q QZP ort .9 9 washed with water (X3) and dried and the solvent was type an mayave at mayonna'se e is removed under reduced pressure. The residual oilwas conslstency distilled in vacuo to give the desired product b.p.

The compositions of the invention may also contain 1 6 6 at l 5 mm Hg 1,2 fg' q 1: Analysis. Calculated for C H O C1 c, 56.4; H, 6.3; f Pest az f y C1, 22.3%. Found: c, 56.7; H, 6.7; CI, 27.3%. herbicidal orfungicidal properties.

The invention is further illustrated in the following 20 EXAMPLES 2 to22 examples Following procedures similar to that of Example 1 furthercompounds were prepared, whose physical characteristics and analyses areset out in Table 1.

TABLE 1 m.p.C, Example Compound b.p.Clmml-lg Analysis refractive index7:C 71H %Cl 2 4-(2.6-dichlorobenzyloxymethyl)- 1416/1.7 Calculated for C..ii,,.o,ci.,; 55.1 5.9 23.3 2 .2.4-trimethy1 l ,3-dioxolane FOLll'ld.55.8 6.2 22.1 3 4-(2.6-dich1oi-obenzyloxymethyl)-4- Calculated for C H Ocl z 59.2 6.4 20.6 methyl-2-spirocyclohexane-1.3- m, 1.5250 Found: 59.06.5 21.9 dioxolane 4 4-( 2.6-dichlorobenzyloxymethyl)4- Calculated for CH O Cb: 58.1 6.1 21.4 methyl-2-spirocyc1opentane-1,3- in, 1.5270 Found:578 6.2 7 6 dioxolane 5 4-( 2,6-dichlorobenzyloxymethyl)-4- Calculatedfor c.,.H,.o,ci,. 60.1 6.7 19.7 ethyl-2-spirocyclohexane-1.3- m, 1.5246Found: 60.1 6.6 20.8 dioxolane 6 4-(2.6-dich1orobenzyloxymethyl )-4-Calculated for C H- o Cl z 59.1 6.4 20.6 ethy1-2-spirocyclopentane-l.3-n 1.5230 Found: 59.0 6.4 21.3 dioxolane 74-(2.6-dichlorobenzyloxymethyl)-2,4- Calculated for C li- 0 ,0 63.8 6.118.0 diethyl-2-phenyl-l.3-dioxolane m.p. Found: 632 6.2 18.8 8 4-(2.6-dichlomhenzyloxymethyl )-2,4- Calculated for C H o Cl- 57 .6 6.621.3 diethyl-2-methyl-l.3-dioxolane m, 1.5098 Found: 58.0 6.8 22.7 9 4-(2.6 dichlorobenzyloxymethyl)-4- Calculated for C ,H O Ch: 60.8 7.5 18.9ethyl-2.2-di-isopropyl-l,3-dioxolane n,,"' 1.5094 Found; 60.2 7.6 20.510 2-benzy1-4( 2,6-dichlorobenzyloxy- Calculated for C H,.,O;,C1,: 63.86.1 18.0 methyl)-4-ethyl-2-metl'iyl-l,3- n 1.5443 Found: 64.5 6.2 19.6dioxolane l l 4-(2,6-dichlorobenzyloxymethyl )2.4- Calculated for C M o-C1,: 56.4 6.3 22.2 diethyl-l.3-dioxo1ane n,,'-" 1.51 18 Found: 56.9 6.522.2 12 4-(2.b-dichlorobenzyloxymethyll- Calculated for C ,H, O,C1,:58.8 7.0 20.4 2.2.4-triethyl-l.3-dioxolane n 1.5090 Found: 58.4 7.1 22.713 4-(2.6-dichlorobenzyloxymethyl )-4- Calculated for C l-1 ,0 0,: 57.76.7 21.2 ethyl-2-isopropy1-1,3-dioxolane n 1.5119 Found: 58.2 6.9 22.914 4-(2.6-dichlorohenzyloxymethyl)-4- Calculated for C ,=,H .,O Cl 53.66.0 21.2 ethy1-2-hydroxymethyI-2-methy1- n 1.5132 Found: 54.0 6.1 21.6 I.3-dioxolane l5 4-(Z-chloi'o-6-fluorobenzyloxymethyl) Calculated forC,,H,,,O;,C1F: 59.5 6.7 1 1.7 4-ethy1-2.2 dimethy1-1.3-dioxo1ane n1.5102 Found: 59.4 6.6 11.4 16 4-(2-chloro-6-fluorobenzyloxymethyl)-Calculated for C H O CIF: 58.2 6.3 12.3 2.2.4-trimethy|-l.3-dioxo1ane n1.5109 Found: 578 6.4 13.4 17 4-(2.6-dichlorobenzy1oxymethyl)-2.2-Calculated for C l-l o Cl 58.0 6.6 21.3 dimethyl 4-n-pi'opyl-l.3-dioxolane 140-3/2mm Found: 589 6.8 22.0 184-(2.6-dichlorohenzyloxymethyl)-4- Calculated for C l-l O Cl z 61.3 7.019.0 n-propyl-2 spiro cyclohexane-l.3 m, 1.5216 Found: 63.3 7.6 18.8dioxolane l9 4 (2.fi-dichloi'ohenzyloxymethyl)-4- Calculated for C M- .00 52.0 5.7 28.7 n-propy12-chloromethyl2-methy1- 168/0. lmm Found: 54.26.0 28.7 1 .S-dioxolane 2O 4-(2.6-dichlorobenzyloxymethyl)- Calculatedfor C t-M0 0 53.6 5.5 24.4 2 .4'dimethy1 l .3-dioxolane 140/1 .OmmFound: 53.3 5.4 24.8 21 4-( 2.6-difluorohenzyloxymethyl)-2.2- Calculatedfor C l-1 0 5: 62.9 7.0 13.3 dimethyl-4-eth)'l-l .3-dioxolane -132/2.0mm Found: 625 6.9 13.4 22 4-12.6-difluorobenzyloxymethyl)Calculated for C H 0 F 61.7 6.7 14.0 2 .2.4-trimeth 1 l .3-dioxolane[ZS/3.0mm Found: 61.4 6.7 13.8

EXAMPLE 23 Herbicidal Activity To evaluate their herbicidal activity,the compounds 6 active material per hectare respectively in a volumeequivalent to 400 liters per hectare. In the soil drench tests onevolume of the acetone solution was diluted to 155 volumes with water andthe resulting formulation of the invention were tested using as arepresentative 5 g at one .mlnagehlevel equwalein to 10 lfllolgramsrange of plants: maize, Zea mays (M2); rice, Oryza o acmie g g v umeequlva em to sativa (R); barnyard grass, Echinochloa crusgalli (BG);alaprolflmate y per g' d pea, Pisum sativum (P); linseed, Linumusitatissium nt epre'emflgence tests untreate .Sown 9' an m (L);mustard1 Sinapis alba (M); and Sugar beet, Beta the post-emergence testsuntreated SOll bearing seedvulgaris (SB) 1mg plants were used ascontrols.

The tests fall into two categories, pre-emergence and The 9 13 z the Q Ew post-emergence. The pre-emergence tests involved z y z y 5 1 i;Sprafymg e O fi l spraying a liquid formulation of the compound onto thea mg t 6 an spliaynagt 501 soil in which the seeds of the plant speciesmentioned 1 5 an g recorded on a I sea l m mates above had recently beensown. The post-emergence no l on the F p 3 mung m mates 3 retestsinvolved two types of test, viz. soil drench and foducnorl m freshwelght of.stem q leaf of the f' of liar spray tests. In the soil drenchtests the soil in which approximately a ratlng 5 lndlcates a reductlonof Seedling plants of 16 above Species were growing, was approximately arating 9 indicates a reduction of drenched with a liquid formulationcontaining a com- 20 zi l f h T bl 2 pound of the invention, and in thefoliar spray tests the e ts 0 t e tests are Set out m a e TABLE 2 DOSAGEPOST-EMERGENCE Example COMPOUND lag/ha SOIL DRENCH FOLIAR SPRAYMZRBGPLMSBMZRBGPL'M SB 2 4-(2,6-dichlorobenzyloxymethyl) l0 7 4 6 O 0 l0 4 3 7 2 8 7 9 2 ,2,4-trimethyl-l ,3-dioxolane l O 0 4 l l l O l4-(2,6-dichlorobenzyloxymethyl)- l0 8 l 8 O O O O 7 2 9 4 8 6 52,2-dimethyl-4-ethyl-l,3- l 4 0 s l 1 0 dioxolane 44-(2,6-dichlorobenzyloxymethyl)- l0 4 3 7 0 0 O 0 6 O B 3 7 5 74-methyl-2spirocyclohexanel l 0 7 3 l S l .3-dioxolane 54-(2,6-dichlorobenzyloxymethyl)- l0 4 3 8 O 0 O 6 3 0 8 2 6 5 74-methyl-2-spirocyclopentanel O O 6 l 2 4 2 1 ,3dioxolane l54-(2-chloro-6-fluorohenzyloxy l0 6 5 7 4 5 2 7 6 (J 7 4 6 0 1 methyl)-4-ethyl-2,2-dimethyl- 1 4 0 5 3 4 0 0 l ,3-dioxolane l74-(2-chloro6-fluorobenzyloxy l0 9 8 8 9 2 2 5 6 2 6 4 7 2 5methyl)-4-methyl-2.2-dimethyll 3 0 4 2 O O (1 l ,3-dioxolane DOSAGEPRE-EMERG ENCE Example COMPOUND kg/ha SOlL DRENCH MZ R 86 P l M SB 24-(2,6-dichlorobenzyloxymethyl)- 10 9 9 9 9 7 6 42,2,4-trimethyl-1,3-dioxolane l 5 9 9 8 2 l O l4-(2,6-dichlorobenzyloxymethy])- l0 9 9 9 9 7 6 32,2-dimethyl-4-ethyl-l,3 l 6 9 9 8 3 3 0 dioxolane 44-(2,6-dichlorobenzyloxymethyl)- l0 9 9 9 3 2 l 54-rnethyl-2-spirocyclohexanel 6 7 9 l 0 0 0 l,3-dioxolane 54-(2,6-dichlorobenzyloxymethyl1 l0 9 9 9 3 5 5 6 4methyl-2-spirocyclopentane l l 6 9 l I O O 1,3-dioxolane l5 4(2-chloro-6fluorobenzyloxyl0 9 9 9 9 6 4 3 methyl)4-ethyl2,2-dimethyll 6 9 9 9 5 2O l.3dioxolane l7 4-(2-chloro-(rfluorobenzyloxyl0 9 9 9 8 5 2 5methyl)4-methyl-2,2-dimethyll 2 7 9 5 l O 0 l.3dioxolane seedling plantswere sprayed with such a formulation. EXAMPLE 24 The SOll used in thetests was a steam-stenllzed, mod- C T ified John Innes Compost mixturein which half the ompara we ests peat, by loose bulk, had been replacedby vermiculite. In these tests the herbicidal activity of 4-(2,6-

The formulations used in the tests were prepared bydichloro-benzyloxymethyl)-2,2-dimethyl-4-ethyl-l,2- diluting with watersolutions of the compounds, in acedioxolane (A) was compared with thatof 4-benzyloxtone containing 0.4% by weight of analkylphenol/ethyymethyl-2,2-dimethyl-4-ethyl-l ,3-dioxolane (B) whichlene oxide concentrate available under the trade name is known from UK.specification No. 1,293,546.

Triton X- l 55. In the soil spray and foliar spray tests the acetonesolutions were diluted with an equal volume of water and the resultingformulations applied at two dosage levels corresponding to 10 and lkilograms of Seeds of the tests species (wheat and blackgrass) were sownin a modified .lohn lnnes Compost mixture in which half the peat byloose bulk, had been replaced by vermiculite. The sown soil was thenwatered and The calculated dosage levels are set out in Table 3, fromwhich it will be seen that the compound (A) is considerably less activethan compound (B) against wheat. At the same time (A) is very activeagainst blackgrass and may therefore be used to combat this weed inwheat crops.

TABLE 3 DOSAGE LEVELS TEST SPECIES (A) (B) SO 90% 1O 5O 90% Wheat 3.27400 400 O,lO 0i3l 1.03 Blackgrass 0,04 0.07 0.19

We claim:

I. A 2,6-Dihalobenzyl ether having the following formula cngoa,

wherein R, represents an alkyl group containing 1 to 6 carbon atoms; Rrepresents an alkyl group containing 1 to 6 carbon atoms, an aryl oraralkyl group up to 8 carbon atoms; R represents a hydrogen atom or analkyl group containing 1 to 6 carbon atoms or R and R together representa polymethylene group of up to 6 carbon atoms and R represents a2,6-dihalobenzyl group.

2. A compound according to claim 1 wherein 2,6- dihalobenzyl group is2,6-dichlorobenzyl, 2-chloro-6- fluorobenzyl, or 2,6-difluorobenzyl.

3. A compound according to claim 2 and having a structure defined byformula I wherein R, is ethyl; R and R are each methyl and R is2,6-dichlorobenzyl.

4. A compound according to claim 2 and having a structure defined byformula 1 wherein R,, R and R are each methyl and R, is2,6'dichlorobenzyl.

5. A compound according to claim 2 and having a structure defined byformula 1 wherein R, is methyl; R and R together form a pentamethylenegroup and R, is 2,6-dichlorobenzyl.

6. A compound according to claim 2 and having a structure defined byformula I wherein R, is ethyl; R and R are each methyl and R, is2-chloro-6-fluorobenzyl.

1. A 2, 6-DIHALOBENZYL ETHER HAVING THE FOLLOWING FORMULA
 2. A compoundaccording to claim 1 wherein 2,6-dihalobenzyl group is2,6-dichlorobenzyl, 2-chloro-6-fluorobenzyl, or 2,6-difluorobenzyl.
 3. Acompound according to claim 2 and having a structure defined by formulaI wherein R1 is ethyl; R2 and R3 are each methyl and R4 is2,6-dichlorobenzyl.
 4. A compound according to claim 2 and having astructure defined by formula I wherein R1, R2 and R3 are each methyl andR4 is 2,6-dichlorobenzyl.
 5. A compound according to claim 2 and havinga structure defined by formula I wherein R1 is methyl; R2 and R3together form a pentamethylene group and R4 is 2,6-dichlorobenzyl.
 6. Acompound according to claim 2 and having a structure defined by formulaI wherein R1 is ethyl; R2 and R3 are each methyl and R4 is2-chloro-6-fluorobenzyl.